Note: Descriptions are shown in the official language in which they were submitted.
W~92/22~83 PCT/US92/~627
211lJ3~
FORM READER WITH LINEAR CCD SCANNER AND DRUM FEED
Backqround of the Xnvention
l~ Field of the Invention
This invention relates to the field of form readers, and in
particular to a reader for discriminating .information on manually
marked forms such as lottery entry tickets as well as printed forms
such as i~sued lottery entry ~alidation tickets. The form is
advanced by a drum feeder including a stepping motor, past an array
of linearly arranged charge coupled device (CCD) light sensors.
The outputs of the CCD light sensors are digitized for each step
of the motor to obtain a ~wo dimensional image of the form for
analysis.
2 Prior Art
Forms for recording handwritten marks for entry of data into
a data proaessing system generally have a plurality of discrete
areas arranged in a pattern delineated by background printing on
the form~ The user indicates a choice by placing a line, an "X"
or other mark (e.g., en~irely filling in the area) in one of a
series of areas presented for choice. Each of the areas is
typically defined by a~box, oval, pair of spaced lines, etc., and
the form normally has a field for a number of such choices~ Forms
of this type are used for example to encode a lottery player's
choice of numbers for :a wager, using a form reader in data
communication with a lottery agent terminal and with a central
lottery computer.
Upon validation of a player's entry thQ lotte~y agent terminal
prints an entry ti~ket showîng the player's entry and a serial
number or other unique identifiGation. The unique identification
may include prin~ed~ alphanumeric characters as well as barcode,
optical character~recognition (OCR) characters and/or darkened
blocks in a geometric pattern representing numeric data. If the
player presents a pr~nted ticket as a winning ticket, the lottery
agent enter~ data *rom the ticke~ into the terminal for verifica-
~ion by the lottery central computer over the data communication
link. This data can be read automatically in the same manner as
a handwritten entry form, using an appropriate scanner.
W0~2/22083 PCT/~Sg2/~627
2~ 3~9
Hand-marked forms are read automatically to determine whether
a mark is present or absent in each of the areas presented for
choice, normally in rows and columns. Printed forms are examined
for the character of printed marks in a given field. The form is
illuminated and the level of light reflected from the form ls
compared to a threshold level. For a row and column form a
photocell can be oriented to read each o~ a number of rows of
delineated areas or ~racks. The level of reflected light along a
track on the form is related in time or po~ition to the pattern
which was print~d on the form to de~ine the columns, ~uch that a
two dimensional array of marks (or missing marks) are determined
to be present on the form. In order to correctly ref~rence the
position on the form with the level of reflected light and obtain
meaningful data, the form must be properly positioned and fed such
that either the rows or the columns are aligned to the sensing
photocells, and the form is properly fed past the photocells such
that by time or position the reflected light signals are accurately
related to position on th~ orm. Bar aode scanners and OCR readers
are similar in that the reflectance of the form in the area of
interest is decoded to ob~ain information from the varia~ions in
darkness of the form.
Certain problems are encountered in attempting to obtain
accurate da~a in:a form reader, partiaularly at relatively higher
speeds, due to the various parameters which may vary in the form
and in the reading process. A form can be misaligned to the
f~eder; the handwritten or printed marks can vary in character and
darkness; the illumination source can vary with aging; the printed
delineations c~n vary in th~ir position on the form; the aard can
flutter transversely as it is fed along its length, ~hereby varying
the refl2ctance level due to changes in the distance between the
marks and the sensors, etc.
To olve these and other problems, the prior art has provided
a number of specific electric and mechanical means for handling the
forms. To improYe correlation of the signal to position on the
form, for example, clocking marks can be printed on the form to
trigger the threshold detector. To better respond to the light
W092/22083 PCr/~S92/04627
211~3~
reflectance variations representing marks, the ~hreshold level of
the comparators can be varied adap~ively. The form feeding
apparatus can be made to high ~olerance, and the forms can be
printed to high tolerance in delineating the areas for potential
marks. These procedures add to the cost and complexity of form
production and form reading apparatus.
In US Pa~ent 4,724,307 - Dutton et al, an array of charge
coupled d~vices (CCDs) is used to sample and hold a two dimensional
representation of the reflectance level over the full face of a
form. The orm is illuminated at a read station. The reflected
image is focused on a tWG dimensional array of discrete CCD
sensors, and the image is parallel loaded into the CCDs all at one
time, charging each of the CCD sensor elements to a level which
represents the level of reflected light at a corresponding area Oæ
the form. The charge leveIs of the sensors are then read out and
digitized, providing a pixel map or numerical representation of the
image of the form. ~ ~
The correlation of the sensor data to the presence or absence
of marks includes finding reference marks in the image and
searching the data for contrasting~edges ~t predetermined positions
in the ~wo dimensional~1mage relative to the reference marks. ~he
individual CCD elements define~picture elements (pixels) which are
substantially smaller~than the~mark areas defined by printing on
the form. By comparing~;several nelghboring pixels, contrasting
edges are detected~ notwithstanding variations in mark darkne~s.
The processor need only~search small areas of the image for the
reference marks, and when located, the positions of the reference
marks accura~ely define the positions of all expected marks
delineated on the form by printing. Moreover, the mark positions
need n~t define rows and~columns.
The device is insensitive to many of the variations which make
it difficul~ to read data~ in prior art form readers O Due to
recordin~ a free~e frame two dimensional image, the reader is
insensitive to form feed variations such as variations ~n feed
rate, ~orm alignment and relative distance between the form and the
source of illumination andtor the detection devices as occurs with
W092/22083 PCT/US92/~627 ~.
3 3 3
A
foxm flutter.
However the ~orm reader according to DuttQn et al, as a
practical matter, requires all the elements of a video camera to
obtain the freeze frame image which is digitized and analyzed. The
two dimensional CCD array and the associated optics for ~ocusing
the image of the full form on the CCD array mak~ the apparatus
relatively expensive compared for example to a line of photocells
for each row or column~ Moreover, elther the form must be advanced
to the read station and stopped, or strobed illumination is needed
to prevent smearing of the image~ These requirements further add
to the expense of the reader, and to some extent make the reader
less convenient for the user.
. ~ . ,
W092/22083 PCT/US92/~627
~1~3~9~
SUMMARY OF THE IMVENTION
It is an aspect of the invention to obtain in a marked form
reader the advantages of two dimensional pixel image data process-
ing while reducing the expense of the reader.
It is a further aspect of the invention to improve the
versatility of a form reader including an image processor to allow
use with forms o~ various formats and sizes, and with handwritten
as well as printed forms.
It is a further aspect of the invention ~o improve the
aonvenience of a form reader for the user, in particular using a
drum ~orm transport which smoothly accepts a form from the user,
reads the form during a continuous advancing motion, and returns
the form smoothly to the user~
These and other aspects of the invention are found in a form
reader especially for lottery forms wi~h handwritten or printad
marks. The orm reader includes a drum transport engaging the
form, and a stepping motor for advancing the form circularly along
a path arou~d the drum, pass~ng through a linear reading station
~longated perpendicular to the path. A light source such as a
linear LED sourae illuminates the form at the read station and
reflect~d light is focused on an elongated array of charge coupl~d
device (CCD) light sensors. A comparator h~ving a threshold baæed
on the maximum and minimum detect~d light levels is used to
digitize the pixels for each CCD light sensor at each step, thersby
defining an X-Y array of light or~dark pixel~. The pixel data is
captured in memory by a frame grabber which can be based on a
programmable logic array circuit. A digital procassor coupled to
an image memory accesses the pixel data and analyzes the data for
predetermined patterns, namely handwritten marks, printed reference
marks, bar code, etc. A throat sensor detects the form at an in~t
to the reader for ini~iating operation of the stepping motor whan
the ~orm is present. Form guides align the form generally to the
transport path, and can be laterally movable for different form
sizes, aligning one or both edges of the form to the transport
path.
W092/22083 PCT/U~92~04~7
3 9 ~
Brief DescriPtion of the Drawinqs
The inven~ion iS discussed herein with reference to exemplary
embodiment~ which incorporate the element~ of the invention;
however, the device is capable of embodiment in other particular
arrangements within the scope of the invention as disclosed and
claimed. In the drawings,
Fig. 1 is an ~xploded perspective view showing the physical
elements and general mounting arrangement according to the
invention;
Fig. 2 is a functional block diagram showlng the operation of
the reader according to Fig. 1;
Fig. 3 is a schematic diagram showing the CCD chip and the
comparison of pixel analog levels to reference white and black
levels;
Fig. 4 is a schematic diagram showing the generation of the
form-present signal;
Fig. 5 is a block diagram showing the stepping motor drive
arrangement; and,
Fig. 6 is a block diagram showing image and dat~ memories, the
bus and bus controller, and microprocessor for image data analysis
and for communication o the results.
.
.
W092~22083 PCT/US92/~27
~1103~!3
Detailed Description ~f the Preferred EmbodimentS
The form read~r of the invention as shown in exploded view in
Fig. 1, and in functional block form in Fig. 2, can be a modular
slement which is either fittable in a casing or incorporated in the
casing o~ a larger terminal such as the casing of a lottery agent
terminal. The reader includes a chassis 20 for mounting the parts
relative to one another and to the casing. Adjacent the ront 22
of the chassis 20, which is accessible to the lottery agent or
other user, a throat opening 24 is defined, having a width
sufficient for the widest form to be processed. For lottery entry
tickets and validated entry tickets, a width o 3.5 ts 4.5 inches
(8.9 to 11.5 om) is appropriate. Lateral guides 28 having barriers
32 are disposed along the edges of the form transport path 40 such
that a form can be placed in the throat opening 24 with one edge
~gainst a guide 28 or with the form guided at both opposite edges
by the barriers 32 of two opposed spaced guid~s 28. This assists
in aligning the form to the transpor~ path 40.
The ~orm need not be aligned exactly accurately if ref~rence
marks are included wher~by the data can be remapped in view of khe
detected locations of the reference marks. Such a procedure is
discussed in connection with a freeze frame image processor in US
Patent 4,72A,307 - Dutton et al, which is hereby incorporated. The
remapped data allows processing of a precisely fed card in a
virtu~l sen~e even if the form is not fed precisely parallel to the
transport path.
At least one of the guides 28 is movable laterally (preferably
both guides) for setting the width of the inlet or throat opening
24, and keeping the form within certain limits of correct align-
ment. The guides 28 can be slidably mounted on a slot at the fron~
22 of the reader for this purpose.
From the throat or inlet opening 24, transport path 40 leads
immediately to a transport drum 52, which is relatively large
compared to the form, for example a~out four inches (10.5 cm) in
diameter. The drum can have a frictional surface for better
engaging the form. The fQrm is held against the drum 52 during
transport, and is thereby kept from fluttering in a manner
W092/~2083 PCT/US92/04627
~1~ 03~
characteristic of forms fed edgewise in a slot. Drum 52 is rigidly
coupled to a shaft 54, which is in turn coupled to drive assembly
60. A toothed belt 62 engages with splined pulleys 66, 66, coupled
respecti~ely to the shaft 54 of drum 52 and to the sha~t of a
stepping motor 70. A~ idler pulley 72 keeps the.belt 62 taut and
together with the ætepping motor 70 ensures that the drum 52 is
driven positively by the drive assembly for advancing the form in
a regular manner stepwise along the transport path 40.
Stepping motor 70 of drive assembly 60 is controlled by a
motor drive circuit 120 (see Fig. 5) to advance the form in steps
around the transport path 40, synchronously with collection of
image data from the form. The motor drive means is activated to
move the form around the drum 52 when triggered by a form-in-
position sensor 140 (see Fig. 3) including a paired LED and
photosensor which are arranged to reflect on the form or are
disposed across the transport path such that the light from the LED
is interrupted by the form at the inlet or throat op~ning 24.
Top guide assembly 80 keeps the form in positive contact with
the transport drum 52. The top guide assembly 80 includes idler
rollers 82 and an arcuat~ cowling 84, which are resiliently mounted
to bear against the~fonm in the direction of transport drum 52, for
holding the form against the drum 52j causing the f~rm to remain
fixed on the surface of the drum as it steps. The drum 52 and top
guide assembly-80 move the~orm into position under an illuminating
means 90 including LED assembly 92, which has a plurality of light
sourcPS disposed across the transport path, for illuminating an
area of the form at ~he rear of the drum 52, elongated in a
direction perpendicular to the transport path 40. ~he LED
illumina~ion source 92 can:illuminate the form ~n a color which is
complementary to any printing on the form which is to be ignored,
for e~ample red light to ignore green printing, etc. Preferably
the reader is arranged to detect handwritten marks in pencil or
pen, as well as black, blue or purple printing on the form. The
light from the ~EDs is: generally directed downwardly and is
inclined to illuminate the form on a rear facing read area 96,
immediately below the illumination assembly 90.
W092t22083 PCT/US92/~627
~liO~99
Toward the rear of the chassis 20, an in~egrated circuit CCD
array 110 is mounted on a holder 112, at the focus of a lens 122
carried in lens assembly 120. The lens assembly 120 has an
alignment base 124 with a depression 126 or mounting a lens barrel
128, and a clamp 132 which holds the lens in place to ocus a
linear imaye of the illuminated portion of the form in the read
area 96 onto the CCD sensor array 110. The CCD sensor array 110
is preferably a single line array of lrO24 x 1 sensor elements, for
~xample part no TCD132~, and ls coupled by a flexible cable 114 to
a printed circuit card 140 mounted in ~he chassis 20 and carrying
circuitry for servicing the CCD sensor element.
As the CCD elements in the array 110 are exposed to lightr a
charge accumulates in each at a rate which is a ~unction of the
degree of illumination of the CCD ~lementr i.e. r depending on the
reflectance of light from source 92 ~rom that portion of the form
whose image is focused on the particular CCD element. The voltages
of the ~ensor elements in the array are read out serially a~d
compared to a threshold in ord~r to digitize the image into light
and dark areas for spatial analysis.
The form is advanced by a stepping operation of motor 70, or
example one step per sample or line of pixels. The motor 70 can
dwell between steps to allow charge to accumulate in the CCD sensor
elements. Th~ sensor array 110 and lens 122 can be placed ~o as
t~ read across the entire width of the form, sr only so much of the
width as includ~s an area bearing marks to be detected. As the
fo~m advances past the:read station 96, the leading edge of the
form;passes under a lower guide assembly 152, which guides the form
outwardly:, back through the throat opening 24 or through a lower
opening in a bezel definlng an upper inlet and lower outlet. The
reading procedure is completed in a relatively short time, each
form being processed in one or two seconds.
The chassis 20 and it contents can be a stand-alone unit, but
preferably are included as a module of a larger terminal. The
chassis is covered by shroud 156 to minimize accumulation o~ dust.
In the event the device is embodied as a stand-alone unit,
appropriate power supplies are required. Preferably, however,
W092/22083 PCT/US~2/~627
2110393
suitable connector~ for data communications and power supply are
provided at an easily accessible area of the chas~is such that the
appaxatus can be ~imply mounted in or on a terminal which will
further process the data read on the card, with power supplied from
the terminal to the reader apparatus.
Fig. 3 illustrates the circuitry associated with ~he detection
of light by the CCD array, and converting the pixel data into bits
for storage and processing. The CCD array iæ preferably coupled
to a regulated supply voltage de~ining a reference voltage level
VREF~ for example from series regulator 210, rendering the sensor
array insensitive to supply variations at voltage Vcc. A filter
capacitor C1 further decouples the power supply. The CCD array
includes inputs coupled to control devices operable activate the
CCD array in synchronlsm with the operation of the stepping motor
70, i.e., during dwells. The CCD is cleared ~o prepare for
collection of pixel data for a given line. When the s~epping motor
dwells after a step, the CCD array 110 accumulates charge in its
sensor elements, which preferably define a linear array. After a
predetermined time, the accumulated charses are clocked out
sequen~ially to an~output ~co~pled to the base of transistor Ql,
which forms an emitter follower with resiætor R1. The inputs to
the CCD array are generally indicated as "READ" ~nd "SHIFT"~ and
select among the claaring,;charge accumulating and output modes of
the device. ~
The ana70g signa~ on;the ba~e of transi~tor Ql is coupled to
two stages defined respectively by operational amplifiers U1-U5 and
U3-U6, and also to the~inverting input of op amp U7. The first of
the two stages includes a sample and hold circuit U~ coupled in a
follower arrangement to op amp U1. Oppositely biased diodes Dl,
D2 and capacitor C2 at the output of U5 form a peak detector.
Similarly, in the second of the stages, the output of op amp U3 is
coupled to a peak detector provided by oppositely biased diodes D3,
D4 and capacitor C3, with resistors R2 and R3 in series with the
diodesO~ The output of the second stage is coupled to a follower
amplifier in U4 and the output of the first stage is coupled to a
follower amplifier in U2. The outputs of U2 and U4 define light
W092/220~3 PCT/US92/~627
~ ~ 1 3 3~
and dark peak levels, and are coupled to a further ~ollower
ampli~ier U6 through series resistors R4 and R5, so as to average
the high and low peaks. The output of follower U6 provides a
refer~nce input to comparator U7, which distinguishes whether a
given pixel voltage is interpreted to be dark or light. The output
of comparator U7 is coupled to the base of driver transistor Q2,
the collector of which is coupled to the power supply voltage Vcc
through resistor R6, and defines the image data ou~put, i.e., a
digital pulse train during unloading of the CCD sensors, corre-
sponding to lines of pixels which were charged over or under the
reference level defined by the average of the high and low peaks.
Operation of the CCD sensor is synchronized to stepping of
drum 52 via stepping motor 70, which commences when a form is
detecting in the inlet opening 24 of the reader. Fig. 4 shows an
exemplary form-in-place:sensor 160, having a paired light source
and photosensor such as LED D5 and phototransistor Q3. The source
D5 and detector Q3 can be located on opposite sides of the form
transport path 40 at the inlet 24 to the reader, or can be arranged
on the same side so as to re~lect off a form. LED ~5 is powered
through resistor R7. :Phototransistor Q3 conducts when rQceiv~ng
light, such that the voltage:at the junction of the collector of
Q3 and resistor R8 falls. The signal is decoupled relative to the
positive supply by capacitor C4, and coupled to one input of
ccmparator UB. : The other; input of comparator U8 defines a
reference voltage via the vol~age divider of resistors R9 and R10.
Resistor R11 pulls up the output of the comparator, which ls high
true.
The stepping motor 70 is a multiple pole motor driven by high
current drivers U9 and U11 in a known manner based upon inputs at
their respective inputs A, B. Sense outputs of drivers U9, Ull ar~
coupled to comparators UlO and U12, and compared to references
voltages generated by voltage di~iders R13-R14 and R16-R17.
Operation of the CCD sensor and the stepping motor are
synchronized using a number of timing and control elements as shown
in Fig. 6 in block diagram form. A first programmable logic array
240, for example Xilex model XC2018-68PLCC, is arranged to collect
W~g2/22083 PCT/US92/04627
;; .
~110339
12
and store the digitized pixel data fxom the image data output at
the collectox of transistor Q2 (see Fig. 3)~ The data is stored
~n a random access image memory 262, via communications across a
sixteen bit bus 250. ~he first lsgic array 240 also provides the
motor enable outputs A,B for ~ach of the high current drivers U10,
Ull for the stepping motor, and the signals for clearin~, reading
and shifting the CCD sensor array 110. A second programmable logic
array 242 provides timing signals for synchronizing operation and
in con~unction with address registers 264 also handles bus address
decoding and control functions necessary for bus arbitration. The
image RAM 262 pre~erably has sufficient storage for a full X-Y
array of pixels on at least one form, and can have storage
sufficient for more than one form.
The data in the image RAM 262 is accessible ov~r bus 250 to
microprocessor 270, which is programmed to analyze the pixel data.
The programming for microprocessor 270 is stored at least partly
in nonvolatile storage a~ EPROM 280. Random access storage is also
provided in RAM 290, which:can be used for further program area,
or for storage of data values. In the embodiment shown~ the
microprocessor 270, its operational m~mory elements 280, 290 and
image memory 262 are~all coupled to the same bus 250. It is also
possible to provide separate busses for the image capture and
control elements 240,~242, 264, 262, and for the data analysi~ ~nd
communicat~on.'elements~270, 280, 290, with ~ppropriate data paths
for allowing the microprocessor access to the contents of image
memory 262 ~ :
Microprocessor 270 can be arranged to analyze pixel informa-
tion in order to detect marks at predetermined locations, prefera-
bly as interpreted in connection with reference marks on the forms.
Dark areas at predetermined locations corresponding to user choices
are found by searching for contrasting edges at the locations,
spanning a plurality of pixels. Barcode is discriminated by
analyzing~for the size and spacing of dark bands disposed perpen-
dicular to a line which may be oriented in any predetermined
direction and at any location on the form. OCR characters are
discriminated by shape patterns at predetermined areas. In each
W092/2~083 P~/US92/04627
9 3
13
case the markings on the form are interpretéd as alphanumeric data
or as choices of options, and are encoded digitally by the
microprocessor. rhe output of the microprocessor, ~or example
numerical data represented by handwritten marks at corresponding
numbered locations, or numerical or alphabetical codes represented
by printed barcode, OCR characters or the like, can be communicated
over bidirectional parallel/serial converter 302 to a ~urther
apparatus suah as a lottery agent terminal in which the reader i5
disposed. The agent terminal conducts further communications with
a central lo~ttery computer for processing lottery entries, ticket
validations, etc. The output and input aan be standard format
RS485, converted between digital logic le~els and RS485 levels by
I/O interface 304, which is di~posed bstween the reader and the
termlnal.
A further sup~rvisory element 310 i5 provided or accomplish-
ing watchdog functions. Supervisory element 310 can include a
power-up reset circuit, power fail detector and watchdog timer for
resetting the apparatus in the event of a failu~e. Supervisory
elem~nt 110 preferably:also controls battery backup means coupled
to the volatile memory elements, for maintaining their contents for
a time after a power failure.
The invention is discussed~with reference to the reading of
lottery tickets and the like, but is also applicable to marked
forms general~y, inclu~ing forms wherein selections are handwrit-
ten, or where a serial number or other indicia is printed on the
form by machine.
According to the preferred embodiment the discrimination
between light and dark pixels is accomplished using an analog
voltage comparator, whereby the pixel levels are dig~tized to a
single bit. This arrangement is inexpensive and effective,
particular because the threshold level applied to the comparator
is a function of the average of the ligh-t and dark peaks. It is
also possible to encode the pixel data using additional bits, thus
defining gray levels.~ Depending on considerations such as
processins speed and expense for additional memory storage
capacity, the pixels can be encoded to only one bit or, using an
W092/22~83 PCT/US92/~627 ~
2ilO39~ 14
analog to digital converter as the digitizer the pixels can be
encoded for examp~e to two, four or eight bits. The analog to
digital converter is simply a threshold detector having a plurality
of thresholds defining gray levels, and can be embod~ed in a manner
simi1ar to the one bit embodiment shown wherein the threshold is
varied to accommodate variations in illumination, average reflect-
ance and the like.
The in~ention having been disclosed, a number of additional
variations within the scope of the invention will now become
apparent to persons skilled in the art. Reference should be made
to the appended claims rather than the foregoing discussion o~
exemplary embodiments, in order to asses the scope of exclusive
rights in the invention claimed.
.
